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The argument

Kant argues that the statement ‘God does not exist’ is not self-contradictory.

Some statements do contradict themselves (e.g. a self-contradictory statement such as ‘a bachelor is a married man’).

But the denial of something isn’t a contradiction. It’s like deleting a sentence; if you’ve deleted it, there’s nothing left to be self-contradictory.

Therefore, the denial of God’s existence isn’t self-contradictory. And because the Ontological Argument rests on God’s non-existence being self-contradictory, it is not sound.

Kant argues that existence is not a predicate.

A predicate is something that adds to the essence of a thing. For example, in the statement ‘the plant is green’ the word ‘green’ is a predicate.

The concept of something existing does not change our concept of the thing itself, just the world in which it now exists.

Therefore, according to Kant, existence is not a predicate. And if it’s not a predicate, it can’t be a perfection. Thus, God can be defined as perfect whether he exists or not.

Useful stories

Kant was born in Königsberg (Prussia) to Johann Georg Kant, a harness maker, in 1724.

Kant managed to climb the University ranks using his exceptional mind, first publishing works on Science, then later moving on to Philosophy. His work was at one time censored by Frederick William II of Prussia because of his view that religion is a purely moral system. But he outlived the King and continued writing until his final illness and death in 1804.